Albon is an antibiotic most commonly prescribed to cats for coccidiosis, a parasitic intestinal infection, though it’s also FDA-approved to treat a range of bacterial infections. The active ingredient is sulfadimethoxine, a sulfonamide drug that works by blocking parasites and bacteria from producing a nutrient they need to survive. It comes as tablets (125 mg, 250 mg, and 500 mg) or a liquid oral suspension, making it relatively easy to dose for cats of different sizes.
Coccidiosis: The Most Common Reason Cats Get Albon
Coccidia are microscopic parasites that invade the lining of a cat’s intestines, causing watery or bloody diarrhea, dehydration, and weight loss. Kittens and cats with weakened immune systems are most vulnerable. Albon is the only FDA-approved drug for coccidia-related infections in dogs and cats, which is why veterinarians have long reached for it as a first-line treatment.
The standard course runs anywhere from 5 to 21 days, typically starting with a higher initial dose on day one followed by a lower daily dose for the rest of treatment. That’s a relatively long regimen, and it’s one of the trade-offs with Albon. The drug is coccidiostatic, meaning it stops coccidia from multiplying but doesn’t directly kill them. Your cat’s own immune system has to finish the job, which is why the treatment window is longer and why very young or immunocompromised cats sometimes need the full three weeks.
An alternative drug, ponazuril, is coccidiocidal, meaning it actually kills the parasites outright. The University of Wisconsin’s Shelter Medicine program recommends ponazuril over Albon for kittens specifically because it works faster and requires fewer doses. However, ponazuril isn’t FDA-approved for this use in cats, so your vet may still choose Albon depending on the situation.
Bacterial Infections Albon Can Treat
Beyond coccidiosis, Albon is approved for a broad list of bacterial infections in cats. These span several body systems:
- Respiratory: tonsillitis, pharyngitis, bronchitis, pneumonia
- Urinary and reproductive: bladder infections, kidney infections, uterine infections
- Skin and soft tissue: abscesses, wound infections, anal gland infections, pustular dermatitis
- Intestinal: bacterial enteritis (gut infections)
The drug is effective against several common bacterial groups, including staph, strep, E. coli, Klebsiella, and Proteus species. Your vet may run a culture or sensitivity test to confirm the bacteria causing the infection will actually respond to sulfadimethoxine before prescribing it, since not all strains are susceptible.
How Albon Works
Sulfadimethoxine belongs to a class of drugs called sulfonamides, which have been around since the early days of antibiotics. It works by mimicking a molecule called PABA that bacteria and coccidia need to make folic acid. Without folic acid, these organisms can’t replicate their DNA or grow. The clever part: cats (and other mammals) get folic acid from food, so they don’t rely on this same pathway. The drug starves the invader while leaving your cat’s cells unaffected.
Because coccidia replicate rapidly and burn through large amounts of folic acid, they’re especially vulnerable to this kind of disruption. The drug doesn’t produce an instant kill, though. It halts reproduction and growth, then the cat’s immune response clears out the remaining organisms over days to weeks.
Side Effects to Watch For
Most cats tolerate Albon well, but the most common side effects are decreased appetite, vomiting, and diarrhea. Since diarrhea is also a symptom of the infections Albon treats, it can be hard to tell whether the drug or the disease is the culprit. If symptoms get worse rather than better after starting treatment, that’s worth a call to your vet.
More serious but less common side effects include dry eye (reduced tear production), liver inflammation that can cause yellowing of the skin or eyes, facial swelling, hives, and joint inflammation. In rare cases, Albon can cause drops in red or white blood cell counts or trigger an allergic reaction.
One risk that’s specific to sulfonamide drugs is crystal formation in the urinary tract. Sulfadimethoxine and its breakdown products can crystallize in the kidneys and bladder, especially if a cat is dehydrated or has very concentrated urine. Making sure your cat drinks plenty of water throughout treatment is genuinely important, not just a nice-to-have. Cats already tend toward concentrated urine, so offering wet food or adding water to meals can help reduce this risk.
Cats That Shouldn’t Take Albon
Albon is not safe for cats that are dehydrated, pregnant, or nursing. Cats with severe liver or kidney disease should not take it either, because the drug is processed through both organs and can worsen existing damage. For cats with moderate kidney disease, vets typically cut the dose in half to reduce the risk of complications.
Cats that are elderly, frail, or have a history of urinary blockages need extra caution. If your cat has ever reacted badly to any sulfonamide drug or related medications like thiazide diuretics, Albon should be avoided entirely.
What to Expect During Treatment
For coccidiosis, treatment typically starts with a loading dose on day one (roughly double the daily maintenance dose), followed by a smaller dose once per day for at least five days. Many cats need 10 to 14 days, and some need the full 21. Your vet will likely want a follow-up stool sample to confirm the parasites are gone before stopping the medication.
For bacterial infections, the length of treatment depends on the type and severity. Skin infections and abscesses may clear up faster than deep respiratory or urinary infections. The liquid suspension tends to be easier to administer to cats than tablets, and most vets will choose it for smaller cats or kittens who need precise dosing.
Improvement in symptoms, particularly diarrhea from coccidia, often shows up within the first few days. If your cat isn’t improving after five to seven days, your vet may reassess whether the infection is responding to the drug or whether a different treatment is needed.